Danzan Ryu Jujutsu was founded by "Henry" Seishiro Okazaki. He was born in Japan on January 28, 1890, and moved to Hawaii as a teenager. At 16, Okazaki learned he had tuberculosis. He dedicated himself to martial arts and recovered completely, which led him to dedicate his life to propagating jujutsu and judo. He created the Danzan Ryu style in 1927-28 by synthesizing several older styles of jujutsu, along with elements of Okinawan karate, Chinese wu-shu, Hawaiian lua, Filipino escrima, and western boxing and wrestling.

Danzan Ryu takes its name from the sweet-smelling Sandlewood trees found on Hawaiian mountains. The name translates as Cedar Mountain or Sandlewood Mountain style. Okazaki's dojo, Kodenkan, means "the school of the ancient tradition." The method of instruction requires senior students to teach less advanced students in the spirit that Master Okazaki declared was inherent in the Hawaiian word Kokua: "to mutually help one another." Okazaki also taught traditional Japanese restorative massage, or seifukujutsu, at the sanitarium where he made his living.